Spontaneous regression of hepatocellular carcinoma after improving diabetes mellitus: possibly responsible for immune system

Abstract

A 60's man was diagnosed as hepatocellula carcinoma at S4/8 and S6 in the liver. Because he suffered from poor control of diabetes mellitus (HbA1c was over 8% for long time), medication of di-peptidyl peptidase-IV (DPP-4) inhibitor was started preoperatively. Befere intaking the DPP-4 inhibitor, the size of tumor in dynamic CT was following; the tumor of S4/8 was 5.0 cm and that of S6 was 2.5 cm. Three weeks after starting medication, the tumor was shrinked respectively; the tumor of S4/8 was 2.5 cm and that of S6 was 2.0 cm. AFP and PIVKA-II were both significantly reduced. Histologically, large number of lymphocytes were infiltrated in a hepatocellular carcinoma, and the infiltrating lymphocytes were proved as CD8 positive T cell by immunohistochemistry staining. We report an extremely rare case of spontaneous regression of hepatocellular carcinoma that is strongly thought to associate with immunoresponse.